Files = library folders. Library folders = Documents, pictures, movies, music (the default folders that come with windows. Settings = logins and desktop
Remove everything wipes windows and installs it as if PC is brand new.
Reset only touches C drive. So if you had 2 partitions on the 1 hdd, and they were C & D, the reset would ignore the D drive. Since you have 2 drives, it will ignore the hdd completely. Put everything on hdd you want to keep and reset ssd.